Many types of panels for floor coverings are known from the state-of-the-art. For the outdoor use, i.e. outside of enclosed rooms, where floors are more or less unprotectedly exposed to weather influences, typically solid wood planks are used, that are impregnated suitably. Such solid wood planks exist in different quality and price levels, wherein in particular tropical woods are preferred for the outdoor use, since those provide particular good weather-resistant properties. However tropical woods are relatively expensive and are suspected to be less environmentally friendly, since a sustained forest industry is often not given in the countries of origin.
For the indoor use, so-called laminate panels have widely spread in the recent years. Laminate panels are relatively inexpensive and have good installing properties. Usually, they are based on a carrier plate of MDF or HDF material, on which surface (front side) several resin-impregnated papers are applied, in particular a decorative paper, as well as a protective overlay paper. To increase the abrasion resistance of the surface resins, such as amino resins are provided with abrasion resistant particles, such as in particular aluminum oxide particles. However, such laminate panels are not suitable to being used in an outdoor area. The carrier plate of MDF or HDF is not moisture-resistant and will inevitably expand due to moisture in the outdoor area. Typically used décor, papers have no sufficient UV-resistance, so that the printings will fade over time, so that the décor will become unsightly after a short time period. Further, the acrylate, respectively melamine resin surfaces do not satisfy the high requirements due to outdoor exposure without any specific modifications.
According to a further development of such laminate panels, so-called direct imprinted panels, were developed. In such direct imprinted panels, usually no papers are used, in particular no décor papers. The décor layer that is a real wood imitation in most cases is directly imprinted on the surface of the panel which is therefore grounded with a suitable primer using emulsion paint in a deep printing process. Document WO2008/061791A1 of the same applicant is a further development of this known state of the art. The disclosure of this document is herewith incorporated by reference. The core of the improvement of this document is that on the surface of a panel two liquid polymer layers are applied wet in wet, so that a partial mixing of the coating mediums takes place. Those two wet in wet coated layers are then cured together, wherein the resulting cured coating has a hardness gradient due to the partial mixing, whereby the hardness of the coating decreases with increasing depth seen from the surface of the resulting coating.
The above-described laminate or direct imprinted panels share the same advantage that the use of so-called click-connecting profiles is possible, in particular specific groove and tongue connecting profiles along the length edge of the panels that allow a simple interlocking by an angle of movement around the interlocking profiles, so that installing the panels is also possible for ordinary persons. Further, the desired décor can be chosen completely freely, since it is imprinted. Therefore, for example, any type of wood can be imitated as well as stone or tile surfaces. The known laminate or direct imprinted panels have in common that they are not suitable for use in the outdoor area. Therefore, it is an object of the present invention to improve the known prior art and in particular to provide improved floor panels for outdoor use that combine the advantages of known laminate panels with respect to flexibility of the décor and simplicity of the installation and with robustness and resistance of real wood planks for the outdoor use. This and other objects that will become apparent during the reading of the following description or that will be recognized by a person skilled in the art are solved with a floor panel according to claim 1 and the use according to claim 19.